And with a framwork you can easily adjust the fonts to your liking. Rounded edges in general? no problem. Rounded arrows? No problem. All icons with background of gray? No problem. Compile to 173x294 pixels? No problem...
It's much much more flexible than any Illustrator format will ever be and it'll allow real collaboration and source code versioning. I think asymptote would be great candidate and it's very close to the DSL I'd like. The good thing is that most of it is also written in asymptote itself so it's very extensible (unlike some other graphics languages)